1. Field of the Invention
The present invention relates to an optical member-holding apparatus which holds a plurality of optical members, a position-adjusting method for adjusting positions of a plurality of optical members, an exposure apparatus in which a plurality of optical members included in an illumination optical system and a projection optical system are held by the optical member-holding apparatus, and a method for producing a device using the exposure apparatus.
2. Description of the Related Art
An exposure apparatus has been hitherto used in the lithography step for producing a semiconductor element, a liquid crystal display element, etc., wherein a pattern, which is formed on a reticle as a mask, is transferred via a projection optical system onto a substrate such as a wafer, a glass plate or the like which is coated with a resist or the like. In recent years, those mainly used as such an exposure apparatus include projection exposure apparatuses of the full field exposure system such as a stepper and of the scanning exposure type such as a scanning stepper.
In the exposure apparatus, those having been hitherto used as an exposure light beam (illumination light beam for the exposure) are the ultraviolet light beams such as the emission line (for example, the i-ray) radiated from a mercury lamp and the KrF excimer laser beam (wavelength: 248 nm). Recently, in order to obtain a higher resolution, other exposure apparatuses are also developed, which use, as the exposure light beam, the far ultraviolet light beam such as the ArF excimer laser beam (wavelength: 193 nm) and the vacuum ultraviolet light beam such as the F2 laser beam (wavelength: 157 nm).
Recently, in order to produce a finer semiconductor element, etc., an EUV exposure apparatus is also developed which uses, as the exposure light beam, a light beam in the soft X-ray region having a wavelength of not more than about 100 nm, i.e., an extreme ultraviolet light beam (hereinafter referred to as “EUV (Extreme Ultraviolet) light beam”). In the case of the EUV exposure apparatus, all components of the illumination optical system and the projection optical system are constructed of reflecting optical elements or catoptric optical elements (mirrors) and a reflection type reticle is used as the reticle as well, because any optical material, through which the EUV light beam is transmitted, is absent at the present time.
Even when any one of the dioptric system, the catadioptric system, and the catoptric system is used as the projection optical system, it is necessary to adjust the image formation characteristics (various aberrations or distortions) of the projection optical system in order to transfer an image of a pattern of the reticle (reticle pattern image) onto the wafer at a high resolution. An adjusting mechanism, which adjusts the position and the posture or attitude of at least a part of the optical members constructing the projection optical system, is generally adopted as a means for this purpose. As for the adjusting mechanism for adjusting the position and the posture, a mechanism is known, which uses a lever and a mechanism for mechanically reducing the movement of the lever (see, for example, Japanese Patent Application Laid-open No. 2002-131605). A parallel link type adjusting mechanism, which adopts a parallel link mechanism, is also known as another adjusting mechanism for adjusting the position and the posture.
When the ultraviolet light beam, the far ultraviolet light beam, or the vacuum ultraviolet light beam is used as the exposure light beam as in the conventional technique, then the reticle can be subjected to the transmission illumination, and the illumination optical system and the projection optical system can be completely separated from each other. Therefore, when a holding mechanism is designed for optical members of one of the optical systems, it has been unnecessary to consider the other of the optical systems. However, in the case of the EUV exposure apparatus, all of the optical members including the reticle are reflecting members. Therefore, it is necessary that a part of optical members (mirrors) for constructing the other of the optical systems (for example, the illumination optical system) is arranged in a barrel of one of the optical systems (for example, the projection optical system). The part of the optical members is exemplified, for example, by a mirror which is included in a plurality of mirrors for constructing the illumination optical system and which is arranged closest to the side of the reticle. When a part of optical members for constructing the other of the optical systems is arranged in the barrel of one of the optical systems as described above, it is necessary that a holding mechanism is designed so that the optical members of the respective optical systems do not shield or intercept the EUV light beam as the exposure light beam, and that the relative positions can be easily adjusted in relation to the plurality of optical members.